outputUnigrams - Whether or not the filter shall pass the original
tokens to the output stream

outputUnigramsIfNoShingles - Overrides the behavior of outputUnigrams==false for those
times when no shingles are available (because there are fewer than
minShingleSize tokens in the input stream)?
Note that if outputUnigrams==true, then unigrams are always output,
regardless of whether any shingles are available.